Well I wouldn't say taking a car is so incerdibly idea, as you said. Taking train is just another, quite good option.
Anyway, pay attention, that in winter, you can easily get to some trables with snow - delays, traffic jams, etc. And can be bit dangerous sometimes. And it will be more expensive - As mentioned, fuel is more expensive, you need to pay toll when you're going on freeway. But driving is not such as crazy and with GPS quite possible. For me Los Angeles is the worst place to drive. No European city can beat that. And you have always option to go, where you want and change planes.